Transition-metal dithiolenes. Part VII. Five- and six-co-ordinate Lewis-base complexes of cobalt and iron bisdithiolenes

Abstract

Treatment of the dimeric dianionic bisdithiolene complexes of iron and cobalt, [MS₄C₄R₄]₂^2–(R = CN and CF₃), [Fe(S₂C₆H₃Me)₂]^– and [M(S₂C₆Cl₄)₂]_n^n–(n= 1 or 2), with Lewis bases such as pyridines, alkyl- and arylphosphines and phosphites, arsines, stibines, and phenylisonitrile, results in the dissociation of the dimers and the formation of five-co-ordinate complexes, [M(L)–(S–S)₂]^–(L = monodentate Lewis base). The monomeric, monoanionic iron bis(toluenedithiolene) forms with pyridines and phosphines weak complexes which are labile in solution; one complex of the corresponding cobalt dithiolene, [Co(PEt₃)(S₂C₆H₃Me)₂]^–, has been obtained. Fission of [FeS₄C₄(CN)₄]₂^2– with CN^–, NCO^–, and N₃^– results in the formation of the unstable complexes [Fe(X)–(S–S)₂]^2–(X = pseudohalide ion).

With bidentate four-electron-donor Lewis bases such as 2,2′-bipyridyl, o-phenanthroline, ethylenediamine, and dimethylglyoxime, six-co-ordinate complexes of the type [M(N–N)–(S–S)₂]^– have been prepared.

The voltammetry of those complexes which were not labile in dichloromethane solution is described, and the spectral and magnetic properties of the complexes are discussed. A tentative MO description of the five-co-ordinate complexes is suggested.